1. Field of the Invention
The present invention relates to polynucleotides associated with breast cancer, a microarray and a diagnostic kit comprising the same, and a method of diagnosing breast cancer.
2. Description of the Related Art
The genome of all organisms undergo spontaneous mutation in the course of their continuing evolution, generating variant forms of progenitor nucleic acid sequences (Gusella, Ann. Rev. Biochem. 55, 831-854 (1986)). The variant forms may confer an evolutionary advantage or disadvantage, relative to a progenitor form, or may be neutral. In some instances, some variant forms confer a lethal disadvantage and are not transmitted to subsequent generations of the organism. In other instances, some variant forms confer an evolutionary advantage to the species and are eventually incorporated into the DNA of most members of the species and effectively becomes the progenitor form. In many instances, both progenitor and variant form(s) survive and co-exist in a species population. The coexistence of multiple forms of a sequence gives rise to polymorphisms.
Polymorphisms include restriction fragment length polymorphism (RFLP), short tandem repeats (STR), variable number tandem repeat (VNTR), single nucleotide polymorphism (SNP), etc. Among these, SNP means a single nucleotide variant form of a polynucleotides present in an individual of the same species. When SNP occurs at coding region sequences, a defective or mutated protein may be expressed by any one of polymorphic forms. On the other hand, SNP may occur at non-coding region sequences. Some of these polymorphisms may result in the expression of defective or variant proteins (e.g., as a result of defective splicing). Other SNPs have no phenotypic effects.
It is known that in the case of a human, SNP occurs every about 300-1,000 bp. When the SNP influences on phenotype such as disease, a polynucleotide including the SNP can be used as a primer or a probe for diagnosing disease. A monoclonal antibody binding specifically to the SNP can also be used for diagnosis of disease and much research is being conducted on analyzing SNP and its function. The base sequence of SNP found in this way and other experimental results are stored in a free database.
Even though findings available to date show that specific SNPs exist on human genomes or cDNAs, phenotypic effects of such SNPs have not been revealed. Functions of most SNPs have not been disclosed yet except few SNPs.
Breast cancer can conventionally be diagnosed by x-ray, ultrasonic diagnosis, and biochemical and molecular biological methods. Among these methods, the molecular biological method cannot be used in an early diagnosis. It was identified by Myriad that about 3 to 30 SNP sites in genes BRCA1 and BRCA 2 are associated with breast cancer. However, most of these sites are used to identify genotypes of patients already diagnosed to have breast cancer and their prices are high. Thus, there is a need for a new SNP site associated with breast cancer.